Scientists in China have developed a new, lower-cost method to upgrade biogas using a porous material called ZIF-8, increasing methane purity from 60% to over 95%.
Biogas from anaerobic digestion (AD) is naturally low in methane, limiting its commercial viability. Traditional upgrading methods, such as membrane separation and pressure swing adsorption (PSA), are effective but costly and energy-intensive. This new approach could make biomethane, a renewable alternative to natural gas, more competitive with fossil fuels.
The push to scale up biomethane is gaining momentum. UK MP Miatta Fahnbulleh stressed at the ADBA (Anaerobic Digestion and Biogas Association) National Conference in December 2024 that, “Anaerobic digestion and biomethane allow us to reduce our reliance on fossil fuels. So we are looking at a transformative decade for this sector.”
What is ZIF-8?
ZIF-8 (zeolitic imidazolate framework-8) is a highly porous metal-organic framework (MOF) that can trap and separate gases at a molecular level. Think of MOFs as ultra-light sponges that selectively absorb certain gases while letting others pass through.
ZIF-8’s pores allow CO2 and hydrogen to pass through while blocking methane, making it ideal for gas separation and upgrading processes.
How it works
The scientists claim that ZIF-8 enhances biological methane production in three key ways:
- Supports microbial growth – Provides a surface for methane-producing microbes, speeding up CO2 conversion.
- Enhances gas transfer – Improves the movement of CO2 and hydrogen, boosting efficiency.
- Increases methane purity – Absorbs CO2 and hydrogen while leaving methane untouched, resulting in higher-quality biomethane.
What it means for biogas
As demand for low-carbon energy grows, cost-effective biogas upgrading will be crucial for making biomethane a viable replacement for fossil natural gas. Lowering costs and increasing efficiency could encourage wider adoption across Europe, Asia, and North America.
According to the European Biogas Association (EBA), “Biomethane is the most scalable and cheapest form of renewable gas available today. It can be used interchangeably with natural gas, making it a critical component in the transition to a low-carbon energy system.”
While ZIF-8 could make biogas upgrading cheaper, biomethane production still faces economic hurdles. Scaling up requires investment in infrastructure, and some argue electrification and hydrogen may be more viable long-term solutions for decarbonisation.
Although the study shows promising results, real-world application is untested at scale. How well ZIF-8 performs outside of a controlled lab setting remains to be seen.
The full study can be viewed .
